Abstract
The commonly used general anesthetic isoflurane induces widespread neurodegeneration in the developing mammalian brain through poorly understood mechanisms. We have investigated whether excessive Ca2+ release from the endoplasmic reticulum via overactivation of inositol 1,4,5-trisphosphate receptors (InsP3Rs) is a contributing factor in such neurodegeneration in rodent primary cultured neurons and developing rat brain. We also investigated the correlation between isoflurane exposure and cognitive decline in rats at 1 month of age. Our results show that isoflurane increases cytosolic calcium in the primary cortical neurons through release from the endoplasmic reticulum and influx from the extracellular space. Pharmacological inhibition of InsP3R activity and knockdown of its expression nearly abolishes the isoflurane-mediated elevation of the cytosolic calcium concentration and cell death in rodent primary cortical and hippocampal neurons. Inhibition of InsP3R activity by its antagonist xestospongin C significantly inhibits neurodegeneration induced by isoflurane at clinically used concentration in the developing brain of postnatal day 7 rats. Moreover, our results show that isoflurane activates β-site amyloid β precursor protein-cleaving enzyme via activation of the InsP3R. We also noted that mice exposed to isoflurane during early postnatal development showed transient memory and learning impairments, which did not correlate well with the noted neuropathological defects. Taken together, our results suggest that Ca2+ dysregulation through overactivation of the InsP3R may be a contributing factor in the mechanism of isoflurane-induced neurodegeneration in rodent neuronal cell culture and during brain development.
Footnotes
- Received September 11, 2009.
- Accepted January 14, 2010.
Y.Z. and G.L. contributed equally to this work.
This work was supported by the National Institutes of Health National Institute of General Medical Science [Grants 1-K08-GM073224-03, 1R01-GM084979-01, 3R01-GM084979-02S1] (to H.W.); and March of Dimes Birth Defects Foundation Research [Grant 12-FY08-167] (to H.W.).
An abstract related to part of this manuscript was submitted to the annual meeting of the American Society of Anesthesiology: Wei H, Liang G, Yang H, and Li J (2008) Suppression of IP3 receptor inhibited isoflurane neurotoxicity in rat primary cortical neurons, Annual Meeting of the American Society of Anesthesiology, 2008 18–22 Oct, Orlando, FL (American Society of Anesthesiology, Park Ridge, IL).
An abstract related to part of this manuscript was submitted to the annual meeting of the Society for Neuroscience: Liang G, Yang H, Li J, Eckenhoff RG, and Wei H (2008) Suppression of IP3 receptor expression inhibited isoflurane-induced neurotoxicity in rat primary cortical neurons, Annual Meeting of the Society for Neuroscience, 2008 15–19 Nov, Washington, DC (Society for Neuroscience, Washington, DC).
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.109.161562.
↵ The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material.
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ABBREVIATIONS:
- ER
- endoplasmic reticulum
- InsP3
- inositol 1,4,5-trisphosphate
- InsP3R
- InsP3 receptor
- LDH
- lactate dehydrogenase
- MTT
- 3-(4,5-dimethyithiazol-2-yl)-2,5-diphenyl-tetrazolium bromide
- MWM
- Morris water maze
- ANOVA
- analysis of variance
- DIV
- day in vitro
- siRNA
- small interfering RNA
- PCR
- polymerase chain reaction
- PI
- propidium iodide
- [Ca2+]c
- cytosolic calcium concentration
- PBST
- phosphate-buffered saline with 0.1% Tween 20
- VGCC
- voltage-gated Ca2+ channel
- BBB
- blood-brain barrier.
- Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics
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